Sun-Seeking Behavior is Linked to Genes: Study
Wed, April 21, 2021

Sun-Seeking Behavior is Linked to Genes: Study


The sunlight, when enjoyed in moderation, has several positive effects on our overall health. It enhances our mood, treats seasonal depression, relieves stress, provides Vitamin D, which is involved in maintaining healthy bone strength, improves sleep, prevents us from eating too much, and helps maintain the efficiency of the human eye. It’s no wonder why there are people who are so drawn to sunlight, flocking to sunny beaches during vacation.

Is sunlight addictive?

However, some people are addicted to sunshine. Harvard-affiliated Massachusetts General Hospital’s chief of dermatology David Fisher previously shared via Harvard Health Publishing that sunlight stimulates the so-called “pleasure center” in the brain and it releases the rush of endorphins and other feel-good chemicals in the body. This is why there may be more than a desire to look good in dark skin. The craving to be exposed in the sun’s rays could be a survival mechanism that is involved for thousands of years as humans need vitamin D.

Since there isn’t much vitamin D in food, the brain rewards people with a rush of pleasure when they get vitamin D through sunlight. Yet, Fisher pointed out that seeking sunlight can also be downright dangerous.



Sun-seeking behavior and genes

A new study conducted by King's College London researchers also suggest that sun-seeking behavior is linked to genes that are involved in behavioral and personality traits, addiction, and brain function. To come up with such findings, the team studied the health information of 2,500 twins from TwinsUK, the biggest twin registry in the United Kingdom. The researchers also analyzed the genetics and the sun-seeking behavior of these participants.

Identical vs. fraternal twins

They found that identical twins in a pair were more likely to have the same sun-seeking behavior compared to non-identical twins, which means that genetics may play a role in why some people are addicted to sunlight. From further analysis of 260 participants from other groups, the researchers have also identified five genes involved in sun-seeking behaviors. Some of these genes have been previously associated with behavioral traits linked to risk-taking and addiction, such as alcohol and cannabis consumption, and having several sexual partners.

Dr. Mario Falchi, the senior author of the study, said via Science Daily that the use of tanning beds and excessive sun exposure may be more challenging now than expected as genetic factors play a role. Such a predisposition must be made aware to the public as it could make people more mindful of the potential harms of too much exposure to the sun or their behavior.

Consultant dermatologist Dr. Veronique Bataille, who was also involved in the study, added that they see people who have “very unhealthy” sun behavior and are aware of it. So, even if they have clear skin cancer risk factors, they may continue to expose themselves to excessive sunlight.

Cities with the most and least sunshine hours

According to mattress review platform Sleepopolis, the top cities around the world with the most annual sunshine hours includes Yuma, US (4,015.3 annual sunshine hours), Marsa Alam, Egypt (3,958.0), Dakhla Oasis Egypt (3,943.4), Calama, Chile (3,926.2), Phoenix, US (3,871.6), Keetmanshoop, Namibia (3,870.0), Las Vegas, US (3,825.3), Tucson, US (3,806.0), Kharga, Egypt (3,790.8), and El Paso, US (3,762.5).

On the other hand, the top cities with the least annual sunshine hours include Totoró, Colombia (637.0), Tórshavn, Faroe Islands (840.0), Chongqing, China (954.8), Dikson, Russia (1,164.3), and Malabo, Equatorial Guinea (1,176.7). Colombia is perceived as a sunny location but it borders both the Pacific Ocean and the Caribbean Sea the reason why it is exposed to higher variety in precipitation and weather patterns. Colombia alone is home to three of the top 10 cities with the lowest sunshine hours per year.

Some cities experience no sun at all for a few months at a time. They call this the Polar Night. These cities include Tromsø, Norway, where winter darkness is enjoyed rather than endured, Svalbard, Norway, and Dikson, Russia.

How much sun is too much?

We all know that too much sun exposure is bad for our skin, but how much sun is too much? The National Center for Biotechnology Information shared the UV Index (UVI), which is a measure of the current intensity of the UVB radiation. The higher the UV Index reading, it also means the higher the radiation level and is more likely a person will get a sunburn. From 0 to 2 UVI, it means low UV intensity while 3 to 5 UVI is considered moderate. On the other hand, 6 to 7 UVI is already considered high UV intensity, 8 to 10 as very high, and 11 as extremely high.

For skin type I, characterized with very light skin, often with freckles, reddish or strawberry blond hair, gray or blue eyes, the maximum amount of time they can be exposed to sunlight is 10 minutes. For skin type II, characterized by light skin, often with freckles, brown or blond hair, UV radiation can lead to sunburn within 20 minutes. Their skin tans only moderately or hardly tan at all.



 As Fisher pointed out, UV radiation from sunlight is the most common and ubiquitous carcinogen in the world. Yet, skin cancer is the most preventable form of cancer because we know its cause: sunlight. A person will know if they are deficient in vitamin D based on a simple blood test at their doctor’s office. The recommended international units of vitamin international units (IU) of vitamin D per day for everyone between 1 to 70 years old is 600 IU. Five to 10 minutes every day outdoors even without sunscreen can help the skin get some natural vitamin D.

Should you need to be out longer than 10 minutes under the sun, it is best to cover up. Use a sunscreen, wear a long-sleeved shirt or long pants, if possible, wear hats or shades, and be cautious in taking medications that may make your body more sensitive to the sun.

The current study by King’s College London researchers shows that genes play a role in regulating risky behavior. The findings also need to be taken into account when policymakers and organizations create a skin cancer awareness campaign.